When irregularly shaped objects are supported on a resilient surface, the surface becomes irregularly loaded, resulting in excessive supportive pressure on parts typically prominent parts of the object, and insufficient support on other parts typically less prominent parts of the object.
According to one aspect of the invention there is provided a support device which includes a plurality of resiliently deformable support units each of which has a pre-compression induced in a load direction, the support units being arranged such that further compression of one support unit in the load direction will cause a reduction in compression of an adjacent support unit.
The support units may be interconnected and the pre-compression is induced by laterally pre-tensioning the support units.
According to another aspect of the invention there is provided a support device which includes a plurality of resiliently deformable support units each of which is laterally connected to at least one other support unit and being configured such that when subjected to a compressive load in a load direction, it deforms laterally in a manner which induces an extensile loading of the at least one other support unit to which it is connected.
The term xe2x80x9cconnectedxe2x80x9d is to be understood to include an arrangement where load transmission between the support units occurs and includes for example where adjacent support units butt against each other, have a positive mechanical connection, or the like.
Each of the support units may be pre-tensioned laterally such that increased compression of one support unit in the load direction will cause a reduction in compression of the at least one other support unit to which it is connected.
The support units may be pre-tensioned by laterally pre-tensioning the support device, e.g. in a peripheral frame. Instead, or in addition, the support units may be pre-tensioned interdependently against each other and/or against internal spacers.
Each support unit may include a pair of ends spaced apart in the load direction and at least one elongate support element extending between the ends and configured to buckle laterally in a predetermined direction when the support unit is subjected to a compressive load in the load direction.
Interconnected support units may be connected together via their support elements, interconnected support elements being configured to buckle in opposite directions usually towards each other.
In one embodiment of the invention the interconnected support elements of interconnected support units may be connected together via connecting members extending laterally between the support elements. The connecting members may be articulated to the support elements. The connecting members may be in the form of struts, preferably, however, the connecting members are flexible and inelastic.
In another embodiment of the invention the interconnected support elements of interconnected support units may be connected directly to one another, e.g. by laterally bearing against each other.
The support device may be a unitary moulding of an elastomeric material.
Each support unit may include a plurality of support elements forming a resilient articulated frame. Each frame may define an octahedron, the support unit including four support elements, each of which has two angularly spaced limbs or parts defining two edges of the octahedron and being configured to deform laterally outwardly when the support unit is subjected to a compressive load in the load direction, the support elements being biased against outward buckling by resilient tensile elements spanning the octahedron internally. The two parts of each support element may be articulated. Preferably the included angle defined between the parts or limbs of a support element is obtuse.
The support device may include a plurality of the support units arranged in an interconnected matrix.
The support device may include at least two layers of support units superimposed one upon the other in the load direction.
The support device may be in the form of a mattress.